The monitoring of flexible pipes, such as production risers, jumpers and flowlines, in subsea hydrocarbon (oil and/or gas) production installations is necessary to avoid potentially catastrophic incidents like hydrocarbon spills, loss of well control and escape of gas, which can affect the buoyancy of floating production, storage and offload (FPSO) vessels. Several techniques to identify damage in flexible pipes have been proposed, as reported in the UKOOA document “Guidance notes on monitoring method and integrity assurance for unbonded flexible pipe”. The techniques commonly used in the offshore oil and gas industry are time consuming and require the production of hydrocarbons to be partially or completely stopped during pipe monitoring.
A system has been proposed in U.S. Pat. No. 7,296,480 for detecting damage or failure of a flexible pipe which uses a strain gauge attached to a connecting structure mounted on the side of a flexible pipe to measure twist in the pipe near a terminal end-fitting resulting from failure of one or more of the reinforcing wires of the pipe structure. Attaching individual strain gauges to a flexible pipe in this manner is not practical due to difficulties in positioning and attaching the strain gauges.